Deciphering the evolutionary history and metabolisms of Epsilonproteobacteria

Despite ongoing attention given to pathogens within the class Epsilonproteobacteria, environmental members are still among the most poorly characterized bacteria. We discovered novel Epsilonproteobacteria all over the world in hostile, sulfur-rich environments, including caves and deep-sea hydrothermal vents. In 2006, we proposed the classification of the family Thiovulgaceae fam. nov. for a large group of terrestrial and marine, environmentally-retrieved sequences (Campbell et al. 2006). However, most of the lineages from terrestrial settings are without cultured representatives and are underrepresented compared to marine-affiliated lineages. There are also unresolved evolutionary relationships between lineages found in cold and hot habtiats, and between lineages found from freshwater versus saline habitats.

Our long-term goal for this project has been to identify and resolve the taxonomic patterns of environmentally-derived Epsilonproteobacteria, and specifically those from terrestrial groundwater systems, so that we can better understand their ecological and geological significance in modern settings. The importance of Epsilonproteobacteria to carbon, nitrogen and sulfur cycling, is just beginning to be appreciated, and our research addresses questions regarding species diversity and microbial interactions with the environment.

Onging and future research focuses on what can be learned about metabolism and mutagenicity from Epsilonproteobacteria living in low-temperature, terrestrial habitats. Certainly, some of the poor evolutionary resolution between the marine and terrestrial lineages at present is because most newly identified lineages within this class are without cultured representatives and have only been described from 16S rRNA-based phylogenetic studies.

Recent Support: Jones Endowment, University of Tennessee

Previous Support: National Science Foundation (DEB-0640835) 2007-2011

Project Collaborators:

Dr. Barbara Campbell, Clemson University (was at University of Delaware during the project)

Dr. Megan L. Porter (was a postdoctoral reseracher on the project, now at the University of Hawaii)

Dr. Janez Mulec (was a postdoctoral researcher on the project, now at the Karst Research Institute, Slovenia)